I believe it typically has chile pepper, roasted orange peel, sesame seeds, Japanese pepper (which I think is called sansho), seaweed and ginger. I'm sure it's possible that other brands have some other special things added to make them unique. I've only had the "House" brand and like it very much. It looks like Amazon sells some other brands, too.

gotcha. well, if you happen to have an Asian grocery nearby they'll definitely have it. but there's a gourmet & restaurant supply store here in LA that sells a really good one, and they have an online store...fair warning that you can get into a lot of trouble once you start browsing ;)